photo: First Solar

Sempra Generation on Wednesday said it has signed a deal for the United States’ largest photovoltaic power plant, a 48-megawatt solar farm to be built by First Solar in Nevada.

The thin-film solar power station will add on to a 10-megawatt solar farm built by First Solar (FSLR) last year adjacent to a Sempra natural-gas fired power plant in Boulder City, Nev., outside of Las Vegas. Sempra Generation CEO Michael Allman told Green Wombat that Wednesday’s deal is part of a strategy to bring 500 megawatts of solar electricity online.

“The initial focus is on projects that are next to natural gas fired plants in the desert Southwest,” said Allman, whose company is a division of San Diego-based power giant Sempra Energy (SRE).

By building solar farms on the site of existing fossil fuel plants, Sempra can plug them in to the existing power grid, cutting costs for land, permits and electricity transmission. The 10-megawatt solar plant in Boulder City went online six months after ground was broken. Allman said Sempra also owns land next to its Mesquite natural gas power plant outside of Phoenix suitable for solar development.

“Those two power plants provide us with a substantial competitive advantage in both timing and cost,” said Allman. “These two initial projects will be the lowest cost energy delivered out of a solar project anywhere in the world.”

He declined to say what that cost is but an executive with PG&E (PCG), which is buying the electricity from the 10-megawatt Boulder City solar farm, previously told Green Wombat that the California utility was “very happy” with the rate it negotiated.

Allman said Sempra owns more than 4,000 acres in Arizona that could generate 300 megawatts of solar electricity. The company has also filed lease claims on 11,000 acres of desert land owned by the U.S. Bureau of Land Management in California’s Imperial Valley. But Allman said Sempra’s preference is to acquire private land to avoid the years-long BLM permitting process. The company will consider a range of solar technologies, including solar thermal, for future solar projects.

The 48-megawatt deal announced Wednesday is contingent upon Sempra signing a power purchase agreement with a utility.

About Green Wombat

Green Wombat is written by
Todd Woody, a veteran environmental journalist based in California who writes for The New York Times, the Los Angeles Times, Grist and Yale e360. He's one of the few people on the planet who have held a northern hairy-nosed wombat in the wild.

Todd formerly was a senior editor at Fortune magazine, an assistant managing editor at Business 2.0 magazine and the business editor of the San Jose Mercury News.